Conventionally a method that uses a die casting is used to manufacture the parts of an automobile such as a cylinder head or manifold, etc., from non-ferrous metal such as aluminum, etc. For the die casting method including gravity die casting, etc that uses die made of such as metal, thermet, etc, various attempts have been made to improve the fluidity of molten metal because if the flow of the molten metal (metal flow) is not carried out smoothly, defects such as minute shrinkage cavities or flow marks are likely to occur on the castings. To improve the fluidity of the molten metal one method is to rectify the flow of the molten metal by forming on the surface of the metal die (surface of cavity) concavo-convex shapes on the surface of a cavity, thereby enabling the molten metal flow on the overall surface of the cavity. A method to improve the fluidity of the molten metal by forming concavo-convex shapes on the surface of the cavity is shown, for example, in Patent Document 1. It discloses a casting die wherein the molten metal is poured uniformly in all parts of the cavity by having square shaped concavities and convexities continuously spread side-by-side over the surface of the cavity of the die, by alternately forming the parts that have high and low flow resistances and by having one side of the square shaped concavities and one side of the square shaped convexities inclined toward the direction from which the molten metal is poured.    Patent Document: JP H07-246450